Content delivery network map generation using passive measurement data

Abstract

A routing method operative in a content delivery network (CDN) where the CDN includes a request routing mechanism for routing clients to subsets of edge servers within the CDN. According to the routing method, TCP connection data statistics are collected are edge servers located within a CDN region. The TCP connection data statistics are collected as connections are established between requesting clients and the CDN region and requests are serviced by those edge servers. Periodically, e.g., daily, the connection data statistics are provided from the edge servers in a region back to the request routing mechanism. The TCP connection data statistics are then used by the request routing mechanism in subsequent routing decisions and, in particular, in the map generation processes. Thus, for example, the TCP connection data may be used to determine whether a given quality of service is being obtained by routing requesting clients to the CDN region. If not, the request routing mechanism generates a map that directs requesting clients away from the CDN region for a given time period or until the quality of service improves.

1. A method operative in a content delivery network request routing mechanism that generates maps for use in directing client requests to subsets of CDN servers, comprising:
 receiving TCP connection data statistics from one or more subsets of CDN servers; and 
 using the TCP connection data statistics to modify a client-to-CDN server mapping from a first CDN server to a second CDN server; 
 wherein the step of using the TCP connection data statistics includes analyzing the TCP connection data statistics on one of: a per CIDR block basis, a per prefix basis, or a per autonomous system (AS) basis. 
 
     
     
       2. The method as described in  claim 1  wherein the TCP connection data statistics are generated on a per connection basis. 
     
     
       3. The method as described in  claim 2  wherein the TCP connection data statistics are generated on a per HTTP connection basis. 
     
     
       4. The method as described in  claim 1  wherein the request routing mechanism includes a map that associates Internet Protocol (IP) address blocks to subsets of CDN servers and that is used to respond to DNS queries. 
     
     
       5. The method as described in  claim 4  further including the step of modifying the map as a function of the TCP connection data statistics. 
     
     
       6. The method as described in  claim 1  wherein the TCP connection data statistics are collected on a per edge server basis. 
     
     
       7. The method as described in  claim 1  wherein the TCP connection data statistics are collected on a per requesting client basis. 
     
     
       8. The method as described in  claim 1  wherein the TCP connection data statistics are collected on a per URL basis. 
     
     
       9. Apparatus for use in a content delivery network request routing mechanism that generates maps for use in directing client requests to subsets of CDN servers, comprising:
 a processor; and 
 computer memory holding computer program instructions that when executed by the processor perform a method comprising: 
 receiving TCP connection data statistics from one or more subsets of CDN servers; and 
 using the TCP connection data statistics to modify a client-to-CDN server mapping from a first CDN server to a second CDN server; 
 wherein the using step analyzes the TCP connection data statistics on one of: a per CIDR block basis, a per prefix basis, or a per autonomous system (AS) basis.